Progress in UV treatment applications requires new compact and sensor constructions. In the paper a hybrid (organic-inorganic) rare-earth-based polymeric UV sensor construction is proposed. The efficient luminescence of poly(methyl) methacrylate (PMMA) matrix doped by europium was used for testing the optical sensor (optrode) construction. The europium complex assures effective luminescence in the visible range with well determined multi-peak spectrum emission enabling construction of the optrode. The fabricated UV optical fibre sensor was used for determination of Nd:YAG laser intensity measurements at the third harmonic (355 nm) in the radiation power range 5.0-34.0 mW. The multi-peak luminescence spectrum was used for optimization of the measurement formula. The composition of luminescent peak intensity enables to increase the slope of sensitivity up to −2.8 mW-1. The obtained results and advantages of the optical fibre construction enable to apply it in numerous UV detection systems.

The paper presents the properties of a strain sensor, which was made using the micro hole collapse method and operates in the configuration of a Mach-Zehnder modal interferometer with a PM-1550-01 polarization maintaining photonic crystal fibre. The sensor’s transfer curve was determined analytically. Its strain sensitivity, determined from measurements, decreases slightly with increasing wavelength and is in a range from −2.01 to −2.23 pm/µε in the wavelength range 1520–1580 nm. Based on the Fourier analysis of the wavelength spectrum of the constructed sensor, the difference of the group refractive indices of the core and the cladding of the photonic crystal fibre was determined, which are in a range from 7.45·10−3 to 1.01·10−2. The temperature sensitivity of the sensor, determined on the basis of measurements performed in a range from 23 to 60◦C, is positive and equals 5.9 pm/K.

A particle-level simulation technique has been developed for modelling fibre suspension flow in a converging channel of a papermachine headbox. The fibre model is represented by a chain of elements connected together. The model was verified by the simulation of rigid fibre dynamics in a simple shear flow. The period of rotation was found to be in a very good agreement with theory and reference data. The model was then employed to simulate fibre motion in a converging channel of a papermachine headbox. Fibre suspension motion was resolved using two-step procedure. Velocity field was calculated by means of a commercial CFD code ANSYS Fluent with RSM turbulence model applied and used as an input to the in-house code allowing to simulate fibre dynamics. Results of the calculations were used to construct the fibre orientation probability distribution (FOPD) which was found to be consistent with available experimental data.

The self-consistent optical-electrical-thermal-gain model of the oxide-confined edge-emitting diode laser has been used to simulate the room-temperature operation of the long-wavelength 1.3-µm quantum-dot (InGa)As/GaAs diode laser. The validityof the model has been verified using some experimental results for comparison. An impact of quantum-dot densityon laser operation characteristics as well as on temperature dependence of lasing threshold have been discussed.

This paper presents the results of computer simulations carried out to determine coordination numbers for a system of parallel cylindrical fibres distributed at random in a circular matrix according to twodimensional pattern created by random sequential addition scheme. Two different methods to calculate coordination number were utilized and compared. The first method was based on integration of pair distribution function. The second method was the modified sequential analysis. The calculations following from ensemble average approach revealed that these two methods give very close results for the same neighbourhood area irrespective of the wide range of radii used for calculation.

The modelling of colloidal fouling and defouling of hollow fibre membranes in the presence of membrane oscillations is analysed by means of numerical simulations as an effect of complex coupling between hydrodynamic and surface forces. To describe the latter the Derjaguin-Landau- Vervey-Overbeek (DLVO) model has been employed. We have investigated the influence of various parameters of the process like flow rate, mean particle diameter, amplitude and frequency of the oscillations, and others, on the efficiency of the defouling process. The investigated parameters is close to that of a silica suspension in , a typical system modelling used to investigate membrane separation. On the basis of numerical simulation results e have defined an optimal set of parameters preventing membrane fouling.

This article presents a linear strain measurement method insensitive to temperature variations and using fibre Bragg gratings. Two Bragg gratings were applied with periods selected to obtain partial coverage of their spectrum characteristics. One of the gratings was subjected to a tension strength. Placing both gratings in one thermal chamber allowed - through ensuring the same thermal conditions - to obtain insensitivity of the entire scheme to temperature variations. The gratings were recorded on the same optical fibre and reacted to temperature variations in the same degree. Value of strain was indicated based on the transmission spectrum characteristic of two grating schemes. The use of transmission, not reflectance, characteristics of the gratings allowed for a direct measurement of the spectrum, without having to use a coupler or optical circulators, and at the same time, this allowed to simplify the strain detection scheme. We proposed applying the continuous wavelet transform with characteristics of the spectrum scheme of two gratings for improvement of static properties. Especially, the thermal linearity and stability of the sensor was improved. For a strain range up to 750 μe, the non-linearity error of processing characteristic obtained was 0.45%. Thermal stability of the scheme proposed was defined as relative sensitivity of the power to temperature variations. The mean value of such relative sensitivity of the scheme proposed in the temperature scope of 21ºC-95ºC, amounted to 0.195.

This study proposes a surface profile and roughness measurement system for a fibre-optic interconnect based on optical interferometry. On the principle of Fizeau interferometer, an interference fringe is formed on the fibre end-face of the fibre-optic interconnect, and the fringe pattern is analysed using the Fast Fourier transform method to reconstruct the surface profile. However, as the obtained surface profile contains some amount of tilt, a rule for estimating this tilt value is developed in this paper. The actual fibre end-face surface profile is obtained by subtracting the estimated tilt amount from the surface profile, as calculated by the Fast Fourier transform method, and the corresponding surface roughness can be determined. The proposed system is characterized by non-contact measurement, and the sample is not coated with a reflector during measurement. According to the experimental results, the difference between the roughness measurement result of an Atomic Force Microscope (AFM) and the measurement result of this system is less than 3 nm.

Real-time monitoring of deformation of large structure parts is of great significance and the deformation

of such structure parts is often accompanied with the change of curvature. The curvature can be obtained

by measuring changes of strain, surface curve and modal displacement of the structure. However, many

factors are faced with difficulty in measurement and low sensitivity at a small deformation level. In order

to measure curvature in an effective way, a novel fibre Bragg grating (FBG) curvature sensor is proposed,

which aims at removing the deficiencies of traditional methods in low precision and narrow adjusting. The

sensor combines two FBGs with a specific structure of stainless steel elastomer. The elastomer can transfer

the strain of the structure part to the FBG and then the FBG measures the strain to obtain the curvature.

The performed simulation and experiment show that the sensor can effectively amplify the strain to the

FBG through the unique structure of the elastomer, and the accuracy of the sensor used in the experiment is

increased by 14% compared with that of the FBG used for direct measurement.

The paper presents a method of measuring the angle of rotation and twist using a tilted fibre Bragg grating

(TFBG) periodic structure with a tilt angle of 6◦, written into a single-mode optical fibre. It has been shown

that the rotation of the sensor by 180◦ causes a change in the transmission coefficient from 0.5 to 0.84 at

a wavelength of 1541.2 nm. As a result of measurements it was determined that the highest sensitivity can

be obtained for angles from 30◦ to 70◦ in relation to the basic orientation. The change in the transmission

spectrum occurs for cladding modes that change their intensity with the change in the polarization of light

propagating through the grating. The same structure can also be used to measure the twist angle. The

possibility of obtaining a TFBG twist by 200◦ over a length of 10 mm has been proved. This makes it

possible to monitor both the angle of rotation and the twist of an optical fibre with the fabricated TFBG.

The paper describes an experimental behaviour of the basalt fibre reinforced polymer composite by external strengthening to the concrete beams. The BFRP composite is wrapped at the bottom face of R.C beam as one layer, two layers, three layers and four layers. The different characteristics – are studied in – first crack load, ultimate load, tensile and compressive strain, cracks propagation, crack spacing and number of cracks etc. To – investigate, total of five beams size 100×160×1700 mm were cast. One beam is taken as control and others are strengthened with BFRP composite with layers. From this investigation, the first crack load is increased depending on the increment in layers from 6.79% to 47.98%. Similarly, the ultimate load carrying – capacity is increased from 5.66% to 20%. The crack’s spacing is also reduced with an increase in the number of layers.

The main focus of this work was the effect of chemical alkaline treatment on Himalayan nettle fibre extraction and the characterization analysis of surface-modified nettle fibre. Nettle fibre is an eco-friendly material naturally grown in the Himalayan hills of India, and it is replacing man-made fibres. The fibres are primarily bound to each other and, in turn, to the core of the plant with pectin, lignin, and gums, which begin to break down through fungal, bacterial, enzymes and chemical treatment action. The stem from the nettle plant is fibrous and has a high-quality fibre to develop nettle yarn, which is utilized to make clothes and handicrafts, mostly aimed at generating livelihood opportunities for the rural tribe’s people. This method of extraction is an effective chemical treatment for enhancing interfacial adhesion between nettle fibres and the epoxy, which is one of the significant challenges to their usage in textiles. In this paper, nettle fibres treated with chemicals such as 1% sodium hydroxide (NaOH), 0.5% sodium sulphite (Na2SO3), 0.05% ethylenediaminetetraacetic acid (EDTA), and 2% acetic acid (CH3COOH). The impact of bacterial and chemical treatments on nettle fibre and untreated nettle fibre was characterized by Fourier transform infrared spectroscopy (FTIR) analysis, which is used to study the functional elements, Scanning electron microscopy (SEM) images revealed that there is a fibre breaking mechanism and cross-section of yarn twist formation, physical and mechanical characteristics were then determined for fibre tensile strength, fibre length, Young’s modulus, elongation break, fineness, and moisture content.

A compact temperature measuring device using a weakly coupled multi-core fibre in the Michelson interferometer structure is proposed and experimentally demonstrated. The device is manufactured by an easy and simple splicing approach which consists of a multi-core fibre segment and an in-fibre coupler. In-fibre coupler is made of a cascaded single-mode fibre and multi-core fibre balls. It enhances the interference phenomenon of light energy between the central core and the outer cores of a multi-core fibre. The sensor shows a high quality fringe visibility of about 14–18 dB in the wavelength spectrum. Multi-core structure presents multi-path interferences and exhibits a maximum temperature sensitivity of 70.6 pm/°C in the range of 20–90°C with an insensitive response to the refractive index in the range of 1.334 to 1.354. The device has the advantages of compact size, easy manufacturing, and it solves cross-sensitivity between temperature and refractive index making it an authentic real-time temperature monitoring solution.

We demonstrated two methods of increasing the bandwidth of a broadband light source based on amplified spontaneous emission in thulium-doped fibres. Firstly, we have shown by means of a comprehensive numerical model that the full-width at half maximum of the thulium-doped fibre based broadband source can be more than doubled by using specially tailored spectral filter placed in front of the mirror in a double-pass configuration of the amplified spontaneous emission source. The broadening can be achieved with only a small expense of the output power. Secondly, we report results of the experimental thulium-doped fibre broadband source, including fibre characteristics and performance of the thulium-doped fibre in a ring laser setup. The spectrum broadening was achieved by balancing the backward amplified spontaneous emission with back-reflected forward emission.

In this paper our results of investigation on a pump power combiner in a configuration of 7×1 are presented. The performed combiner, with pump power of 80–85% transmission level, was successfully applied in a thulium doped fibre laser. The performed all-fibre laser setup reached a total CW output power of 6.42 W, achieving the efficiency on a 32.1% level

In this work studies on propagation properties of a microstructured polymer optical fibre infiltrated with a nematic liquid crystal are presented. Specifically, the influence of an infiltration method on the LC molecular alignment inside fibre air-channels and, thus, on light guidance is discussed. Switching between propagation mechanisms, namely the transition from modified total internal reflection (mTIR) to the photonic bandgap effect obtained by varying external temperature is also demonstrated.

The etiology of Postpartum dysgalactia syndrome (PDS) includes stress οn preparturition and constipation associated with low water intake or low fiber intake. The aim of this study was to investigate the effects of a raw crude fibre concentrate (Arbocel®) on sow’s metabolism and performance.
100 sows from a farm suffering from PDS, were divided into two groups, with equal distribu- tion of their parity (1 to 5 parity): a) T1 group (control group): 50 sows were fed with regular gestation feed (GF), pre-farrowing feed (PFF), and lactation feed (LF), b) T2 group: 50 sows were fed with regular GF, PFF and LF supplemented with topdress Arbocel® from 104th day of gestation until 7th day of lactation). Health parameters [faeces score (FS), PDS score (PDSS), body condition score (BCS)], performance parameters and liter characteristics were recorded. Blood samples were collected from 25 sows / group (5 sows per parity) 24 h after birth of last piglet and on 14th day of lactation for the evaluation of insulin, leptin and ghrelin levels in the serum, using commercial ELISA kits.
In T2 group, BCS at farrowing (p<0.001), FS (p=0.001) and PDSS (p=0.003) were improved significantly. The number of piglets stillborn and dead due to crushing decreased (p=0.001), while the number of liveborn (p=0.016) and weaned piglets (p=0.001) increased in T2 group. Moreover, in T2 group, the BW of piglets at weaning was higher (p<0.001). A significant increase of insulin (p=0.032) and leptin (p=0.032) levels in serum was noticed in T2 group 24 h after farrowing. In conclusion, the supplementation of extra crude fibre in breeding stock with PDS problems due to nutritional imbalance has beneficial effects on their health and performance.

Natural fibres have recently gained attention as an alternative sustainable material for civil engineering applications due to natural fibres’ exceptional performance, including high strength, and their environmental-friendliness and cost-effectiveness. However, there are disadvantages to using natural fibres in extreme environments. Therefore, this paper reviewed the effect of moisture content and temperature on the tensile strength of potential natural fibres for engineering purposes. Furthermore, this paper also critically reviewed the influence of alkaline treatment on natural fibres’ tensile strength. This is significant because alkaline treatment enhances surface friction and the fraction of the revealed cellulose on the fibres’ surface, resulting in better mechanical interlocking. In conclusion, natural fibres demonstrate their potential for geotechnical applications due to the materials’ strong tensile properties after being subjected to treatment processes.

In this paper, we present a fibre-optic sensor for simultaneous measurement of refractive index and thickness of liquid layers.We designed an experimental low-coherence setup with two broadband light sources and an extrinsic fibre-optic Fabry–Pérot interferometer acting as the sensing head.We examined how the refractive index of a liquid film and its thickness affect spectrum at the output of a fibre-optic interferometer. We performed a series of experiments using two light sources and only one sensing head. The spectra were collected in ranges of 1220÷1340 nm and 1500÷1640 nm. The obtained results show that using two spectra recorded simultaneously for two wavelength ranges enables to determine thickness in a range of 50÷500 μm, and refractive index of a liquid film in a range of 1:00÷1:41 RIU using only one sensing head.

This paper presents a non-invasive measurement method for simultaneous characterization of diameter and refractive index of transparent fibres. The method is based on scattering of a polychromatic beam of light by a side-illuminated fibre under study. Both quantities of interest are inversely calculated from the scattering far-field region in the vicinity of the primary rainbow. The results of practical measurements are examined with the use of a novel optical system for laboratory-level tests. An analysis of prediction errors for 20– 120 μm thick fibres having various refractive indices helps to assess the outcome of the measurement data. The results show a clear route to improve the measurement process in on-line industrial process control.

As part of the work, the error level of simulations of uniform optical-fibre Bragg gratings was determined using the transitionmatrixmethod. The errorswere established by comparing the transmission characteristics of the structures obtained by simulation with the corresponding characteristics arrived at experimentally. To compile these objects, elementary properties of the characteristics were specified, also affecting the applications of Bragg gratings, and compared with each other. The level of error in determining each of these features was estimated. Relationships were also found between the size of the physical properties of Bragg gratings and the level of errors obtained. Based on the findings, the correctness of the simulation of structures with the said method was verified, giving satisfying results.

The aim of the research was implementation of fibre Bragg grating sensors and the Aramis system to monitor strain, displacement and stress values in new materials used in the building industry. Selected elements of a residential building made of the Polytech material with a 60% content of the EPS granulate from recycling were tested: a prefabricated wall with a lintel, a reinforced concrete floor slab, a lintel, a reinforced concrete column and a wall. Long-term testing was also carried out taking account of changes in environmental conditions. The methodology of the research was based on the development of purpose-made dedicated FBG strain sensors, laboratory calibration and the embedding of the sensors in the tested element structure. The proposed system of continuous measurements made it possible to determine real strain, displacement and stress values in selected elements of the Polytech structure for a facility founded in a difficult geotechnical terrain (subsoil).

This paper presents the results of the static work analysis of laminated veneer lumber (LVL) beams strengthened with carbon fabric sheets (CFRP). Tested specimens were 45mm wide, 100 mm high, and 1700 mm long. Two types of strengthening arrangements were assumed as follows: 1. One layer of sheet bonded to the bottom face; 2. U-shape half-wrapped reinforcement; both sides wrapped to half of the height of the cross-section. The reinforcement ratios were 0.22% and 0.72%, respectively. In both cases, the FRP reinforcement was bonded along the entire span of the element by means of epoxy resin. The reinforcement of the elements resulted in an increase in the bending strength by 30% and 35%, respectively, as well as an increase in the global modulus of elasticity in bending greater than 20% for both configurations (in comparison to the reference elements).